From: Tao Ma <boyu.mt@taobao.com>
Date: Wed, 26 Sep 2012 04:08:57 +0000 (-0400)
Subject: ext4: don't call update_backups() multiple times for the same bg
X-Git-Tag: v3.7-rc1~91^2~28
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0acdb8876fead922c9ffa6768c5675a37485c48c;p=pandora-kernel.git

ext4: don't call update_backups() multiple times for the same bg

When performing an online resize, we add a bunch of groups at one time
in ext4_flex_group_add, so in most cases a lot of group descriptors
will be in the same group block. But in the end of this function,
update_backups will be called for every group descriptor and the same
block will be copied and journalled again and again.  It is really a
waste.

Fix things so we only update a particular bg descriptor block once and
skip subsequent updates of the same block.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

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